Sizing paper and product



Patented July 20, 1954 UNITED STATES A'E'ENT QFFICE SIZING PAPER ANDPRODUCT poration of Delaware No Drawing. Application May 13, 1948,Serial No. 26,928

6 Claims.

This invention relates to methods, and particularly to the use ofaqueous dispersions capable of markedly increasing the efiiciency ofordinary rosin dispersions in the engine sizing of paper pulp.

It is customary at the present time to engine size paper pulp by mixingwith a suspension of the pulp a dilute aqueous dispersion of rosin whichhas been at least partially neutralized with alkali. The rosin is thenprecipitated, coagulated and fixed on the pulp by adding to thesuspension a small quantity of aluminum sulfate (known as alum in thepapermakers art), usually about 1% by weight of the dry pulp. Thedispersed rosin may be added in varying amounts, depending upon theresults desired, but is usually added in amounts between and 4% based onthe weight of the dry pulp being treated.

One of the objects of this invention is to provide a method of improvingthe sizing efiiciency of ordinary rosin size dispersions such as thosedescribed above.

A further object of the invention is to provide a sizing adjunct which,when employed in combination with rosin or other sizing agents in theengine sizing of pulp suspensions, not only provides a considerablyhigher degree of sizing than an equivalent amount of rosin alone, butalso permits equivalent sizing with much lower rosin dosages.

Still further objects and advantages of the invention will appear fromthe following description and appended claims.

improved sizing The methods of the invention are carried out in generalby first adding to the beater a pre determined amount of pulp in theformof a dilute aqueous suspension, after which a dilute aqueousdispersion of rosin which has been at least partially neutralized withcaustic alkali,

soda ash or the like, is added in an amount sufficient to supply from to4% of rosin based on the weight of the dry pulp used. A dilute aqueousdispersion of the reaction product of rosin with an acidic compoundcontaining the -CO-C=C group, which product has also been at leastpartially neutralized with alkali, is then added, preferably in anamount sufiicient to supply between 20 and 50% of the reaction productbased on the weight of the rosin employed. The dispersed mixture ofrosin and resinous reaction product contained in the pulp is then fixedto the pulp fibres by adding a small amount of aluminum sulfate to thebeater and thoroughly mixing the same with the treated pulp suspenmon.

Although the rosin, resinous reaction product and aluminum sulfate arepreferably added to the pulp in the order described above, it is alsopossible to add the resinous reaction product first, and then the rosin.Moreover, the aluminum sulfate may be added at any stage, and if desiredall of the above sizing materials may be added to the pulp at one time.

Suitable acidic compounds containing the CO-C=C group include alpha-betaunsaturated polybasic organic acids or acid anhydrides, such as maleic,fumaric, itaconic and citraconic acids and their anhydrides. Thus,broadly the materials which are adapted to improve the sizing efiiciencyof rosin according to this invention include the reaction products ofrosin with a compound of acidic character containing the CO--C=C group,such as those referred to above. The most suitable resinous reactionproduct for the purposes of this invention, however, is the resinprepared from rosin and maleic anhydride. For the sake of simplicity,therefore, reference will be made primarily to the above resin infurther describing the details and variables of the invention.

The reaction product per se is generally prepared by heating maleicanhydride with rosin, at 160 to 170 C. for about four hours. The amountof maleic anhydride employed may be varied from about one-quarter to onemol for each mol of rosin, and in many instances some- What lower orhigher temperatures than the above may be used. If lower temperaturesare used a longer period of heating than four hours may be required,while if higher temperatures are used, the heating period may frequentlybe reduced.

In charging the beater with the above reaction product, it is necessaryto first form an alkaline dispersion of the resin in water to facilitatethorough mixing of the reaction product with the pulp. This ispreferably accomplished by first forming a preliminary dispersion ofrelatively high concentration, after which the concentrated dispersionmay be diluted to the desired extent. In general, the rosin-maleicreaction product, caustic soda or other alkali and water are heated andsimultaneously stirred in any suitable reaction vessel at temperaturesbetween about 140 and 200 C. The various ma-- terials used may be addedin amounts varying from about 50 to of reaction product, 4 to 14% ofalkali, and 6 to 46% of water. The charge is finally cooled down to 60to C., depending upon the amount of reaction product employed, and isthen removed, whereupon it cools to a consistency varying from a viscousfluid mass to a hard and brittle solid, which may be ground to a powder.For example, when say 57% of the reaction product, of caustic soda and38% of water are employed, the resulting dispersion is in the form of aviscous fluid, while when say 80% of the reaction product, 7% of causticsoda and 13% of water are employed, the dispersion in is the form of ahard and brittle solid.

In preparing the secondary or dilute dispersion from the primarydispersion, the latter dispersion is diluted with from 1500 to 4000parts by weight of water for each 100 parts by weight of the dispersiondepending upon the amount of reaction product in the dispersion. Themixing is preferably accomplished with the aid of vigorous stirring andat temperatures varying from to 65 C., depending upon the amount ofreaction product present in the primary dispersion. In all instances theresulting product is in the form of a milky dispersion which does notsettle to any great extent upon standing.

In using the above milky dispersion as a sizing adjuvant, the beater isfirst charged with a predetermined amount of pulp, after which the rosinsize is added in the form of a dilute aqueous and partially or whollyneutralized dispersion in amounts capable of supplying from about to 4%of rosin based on the weight of the dry pulp used. The dilute dispersionor" rosin-maleic reaction product prepared as described above is thenadded to the pulp suspension in an amount sufficient to supply from 20to 50% of the rosinmaleic reaction product based on the weight of therosin used. After thoroughly beating the mixture the pulp is then readyfor the addition of aluminum sulfate or like fixing agent, which may beadded in amounts varying from about 1 to 5% based on the dry pulpweight, depending upon the type of paper which it is desired to make. Aspreviously indicated, however, the various materials employed may beadded in any desired order, or simultaneously.

A further understanding of the invention will be obtained from thefollowing specific examples of methods of using the sizing adjuvants ofthe invention.

Example I A paper beater was first charged with 40,000 pounds of asulfite pulp suspension containing about 5% of dry pulp. To the chargewas then added about 30 pounds of rosin in the form of a rosindispersion which was 70% neutralized and contained 0.29 pound of rosinper gallon of dispersion. The rosin dispersion was beaten into the pulpfor about one-half hour, after which an alkaline dispersion ofrosin-maleic anhydride reaction product, prepared by reacting rosin withmaleic anhydride, partially neutralizing the reaction product anddispersing the neutralized product in suiiicient water to produce adispersion containing 0.29 pound of reaction product per gallon, wasadded in an amount sufiicient to provide about 6 pounds of the reactionproduct. The resulting mixture was beaten for about one-half hour, afterwhich about 5% of aluminum sulfate based on the weight of the dry pulpwas added. After a further half hour of beating, the stock was made intopaper, which upon being tested by the standard ink penetration testshowed 28 minutes sizing. The same stock sized with 62 pounds of rosinin the form of a 70% neutralized rosin dispersion, but without theaddition of the rosin-maleic anhydride reaction product, showed 26minutes sizing. Thus, it was possible to obtain better sizing by usingrosinmaieic anhydride reaction product in conjunction with the rosin,even though more than twice as much rosin was used in the absence or"the reaction product.

The extent to which a given sheet of paper is sized is generallyexpressed in units of time, as for example, the number of seconds orminutes required for a given liquid, such as water, ink or the like, topenetrate the sheet to a predetermined degree. The liquid used, the endpoint taken, and the method of determining the arrival of the end pointvary, and as a result the numerical values obtained by diiierentobservers vary quite widely. It is noteworthy however that thecomparative values for different kinds or samples of paper are verynearly the same, regardless of the test method employed.

Example II A small paper beater was charged with 132 grams of an alphapulp suspension containing about 1.7% of dry pulp. To the charge wasthen added about 2 grams of rosin, or 1.5% based on the weight of thedry pulp, in the form of a rosin dispersion which was 70% neutralizedand contained 10 grams of rosin per liter of dispersion. The rosindispersion was beaten into the plup for about 15 minutes, after which analkaline dispersion of rosin-maleic anhydride reaction product was addedin an amount sufficient to provide about 0.4 gram of the reactionproduct or 20% based on the weight of the rosin used. The resultingmixture was beaten for about 15 minutes, after which about 1% ofaluminum sulfate based on the weight of the dry pulp was added. Afteranother 15 minutes of beating, the stock was made into paper, which uponbeing tested by the standard ink penetration test showed seconds sizing.The same stock sized with 2 grams of rosin in the form of a 70%neutralized rosin dispersion, but without the addition of therosin-maleic anhydrid reaction product, showed only 29 seconds sizing.

Example III One hundred and thirty-two grams of an alpha pulp suspensioncontaining about 1.7% of drr, pulp were treated in the manner describedin Example II, but using 1 gram of rosin, or 0.75% based on the weightof the dry pulp, and 0.2 gram of the rosin-maleic anhydrid-e reactionproduct, or 20% of the weight of the resin used. .After making paper ofthe resulting stock, the paper was tested by the standard inkpenetration test and showed 61 seconds sizing. The same stock sized with1 gram of rosin in the form of a 70% neutralized rosin dispersion, butwithout the addition of the rosin-maleic anhydride reaction product,showed only 5 seconds sizing.

Example IV To 1500 cc. of a suspension of bleached Gatineau sulfite pulpin water containing 30 grams (2%) of dry pulp were added with agitation0.2 gram of rosin in the form of an alkaline dispersion in water, whichwas 70% neutralized and contained 30 grams of rosin per liter ofdispersion, and 0.1 gram of rosin-maleic anhydride reaction product inthe form of an alkaline dispersion in water which was 50 neutralized andcontained 30 grams of the reaction product per liter of dispersion. Theresulting mixture was agitated for about 15 minutes, after which about3.5% of aluminum sulfate on the weight of the dry pulp was added. Afteranother 15 minutes of agitation, the stock was made into paper, whichupon being tested by the standard ink penetration test showed 320seconds sizing. On sizing the same stock. in the same manner asdescribed above, but applying 0.3 gram of resin in the form of a 70%neutralized dispersion instead of the combination of rosin androsin-maleic anhydride reaction product, and on testing the paperprepared therefrom by the ink penetration method, only 122 secondssizing was obtained.

Example V A suspension of bleached Gatineau sulfite pulp was preparedand sized in the manner described in Example IV, but using sufficient ofthe alkaline dispersions to provide 0.4 gram of rosin and 0.2 gram ofthe rosin-maleic anhydride reaction product. In this instance, thedispersion of the rosin-maleic anhydride reaction product was 100%neutralized. Paper prepared from the resulting stock showed 4'71 secondssizing on being tested by the ink penetration method, while paper whichhad been prepared and sized in the same way, but using 0.6 gram of rosininstead of the combination of rosin and rosin-maleic anhydride reactionproduct, showed only 155 seconds sizing. Example VI Alkaline dispersionsof rosin and rosin-maleic anhydride reaction product were prepared containing 30 grams per liter of rosin and the reaction product,respectively. The rosin dispersion was '70 neutralized, and thedispersion of the reaction product was 50% neutralized. Sufficient ofthese dispersions were added to 1500 cc. of a suspension of bleachedGatineau sulfite pulp containing 30 grams of dry pulp to deposit 0.225gram of rosin and 0.075 gram of rosin-maleic reaction product on thepulp. The resulting mixture was agitated for about 15 minutes, afterwhich 3.5% of aluminum sulfate on the weight of the dry pulp was added.After another 15 minutes of agitation, the stock was made into paper,and was tested by the standard ink penetration method, showing 283seconds sizing. On sizing the same stock in the same manner as describedabove, but applying 0.3 gram of rosin instead of the combination ofrosin and rosinmaleic anhydride reaction product, and on testing thepaper prepared therefrom by the ink penetration method, only 122 secondssizing was obtained.

Similar tests were made on alpha pulp, using rosin alone as well asrosin in combination with other resinous reaction products of thegeneral class hereinbefore described, but otherwise following themethods of Examples II and III. .The amount of sizing obtained with thevarious sizing agents or combinations of sizing agents used is given inthe following table:

It is to be understood that the per cents of rosin referred to in theabove table are based on the weight of the dry pulp being treated, whilethe per cents of resinous reaction product are based on the weight ofthe rosin used.

In order to show further the efiectiveness of the sizing adjuvants ofthe present invention, comparative tests were made with various kinds ofpulp and with varying amounts of the sizing agent, using the standardink penetration method. This method, which is one of the most commonlyused, involves making a boat of a test sheet of previously sized paper,floating the same upon a bath of ink, and noting the time (usually inseconds which passes before a shade of coloration appears on the uppersurface of the sheet. In each instance certain samples of the testpapers were sized with a rosin dispersion alone, while other samples ofthe same kinds of paper were sized with the rosin dispersion andproportional amounts of the rosin-maleic reaction product dispersionprepared as hereinbefore described. To reduce variables to a minimum,the tests were made in each instance with a dispersion of G grade rosinwhich had been 70% neutralized, with the use of 1% of aluminum sulfatebased on the weight of the dry pulp, and with the final pulp suspension(after the sulfate addition) at a pH of 4. In each of those instanceswhere the rosin-maleic reaction product was used in conjunction with therosin, it was employed in an amount equal to 20% of the weight of therosin employed.

The results of the various tests are given in the following tables:

BLEACHED KRAFT PULP Rosin+Rosin- Rosin Alone Maleic Reaction ProductSeconds Percent Seconds Percent Rosm 'zing Rosin Sizing S ULFITE P ULPSRosin+ Rosin- Rosin Alone Maleic Reaction Product Seconds PercentSeconds Percent R051 Sizing Rosin Sizing RA G P ULP Rosin+Rosin- RosinAlone Maleic Reaction Product Seconds Percent Seconds Peceut SizingRosin Sizing ALPHA PULP Rosin+ Rosin- Maleic Reaction Product RosinAlone Percent Rosin Seconds Seconds Sizing Percent Rosin Sizing Theabove tables clearly show that the eniciency of rosin as a sizingmaterial is markedly increased, when rosin-maleic reaction product isemployed therewith to the extent of 20% by weight of the rosin. Thus, itis possible to obtain either a much larger amount of sizing with anequivalent amount of rosin, when the rosinmaleic reaction product isemployed, or the same degree of sizing may be obtained with considerablyless rosin. This is of great advantage to the papermalrer, particularlyin those instances where it is, desired to obtain a maximum amount ofsizing at minimum cost. In the preparation of the dispersions of rosinor the resinous reaction products of the invention, it is usuallynecessary to first prepare a relatively concentrated dispersion, as itis difiicult to form dilute dispersions directly without employingexcessive amounts of alkali. Moreover, the preparation of a preliminaryconcentrated dispersion is of considerable advantage to the papermaker,who usually does not make his own sizing agents as it permitsconsiderable saving in freight. It is possible in some instances to addthe concentrated dispersion directly to the beater without first forminga dilute dispersion, but in general it is preferable to dilute thedispersion before adding it to the beater. In preparing dispersions ofthe resinous reaction products, the reaction product is partly or whollyneutralized with caustic soda, caustic potash, soda ash or other alkalimetal base.

Although it is possible to employ the resinous adjuncts of the inventionin widely varying amounts, it is usually not practical to employ lessthan 20% or more than 50% of the reaction product based on the weight ofthe rosin used. Smaller amounts do not increase the sizing efficiency asmuch as is usually desired, while larger amounts give less and lessincrease in sizing as the amount is increased.

This application is a continuation-in-part of Serial No. 538,708, filedJune 3, 1944, which was a division of Serial No. 452,670, filed July 28,1942, both now abandoned.

What is claimed is:

1. The method of sizing paper which comprises charging a beater with apredetermined amount of paper pulp, adding to the pulp a sufiicientamount of an aqueous and at least artly neutralized dispersion of rosinto supply from to 4% of rosin based on the weight of the dry pulp,beating the rosin dispersion into the pulp, thoroughly mixing with thethus treated pulp a sufiicient amount of an aqueous and at least partlyneutralized dispersion of the reaction product of 1 mol of rosin andfrom about 0.25 to 1 mol of maleic anhydride to supply from 20 to 50% ofsaid reaction product based on the weight of the pre viousiy addedrosin, and then admixing with the pulp about 1 to 5% of aluminum sulfatebased on the weight of the dry pulp.

2. Paper sized with to 4% of rosin, 1 to 5% of aluminum sulfate based onthe fiber, and 20 to 50%, based on the weight of the rosin, of thereaction product of 1 mol of rosin and from about 0.25 to 1 mol ofmaleic anhydride.

3. Paper sized with /4 to 4% of rosin,1 to 5%:

of aluminum sulfate based on the fiber, and 20 to 50%, based on theweight of the rosin, of the reaction product of 1 mol of rosin and fromabout 0.25 to 1 mol of fumaric acid.

4. Paper sized with /4 to 4% of rosin, 1 to 5% of aluminum sulfate basedon the fiber, and 20 to 50%, based on the weight of the rosin, of thereaction product of 1 mol of rosin and from about 0.25 to 1 mol ofcitraconic acid.

5. Paper sized with /q. to 4% or rosin, 1 to 5% of aluminum sulfatebased on the fiber, and 20 to 50%, based on the weight of the rosin, ofthe reaction product of 1 mol of rosin and from about 0.25 to 1 mol ofitaconic acid.

6. Paper sized with A; to 4% of rosin, 1 to 5% of aluminum sulfate basedon the fiber, and 20 to 50 based on the weight of the rosin, of thereaction product of one mol of rosin with from about onequarter to onemol of a compound selected from the group consisting of maleic, fumaric,itaconic and citraconic acids and their anhydrides.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,978,598 Peterson Oct. 30, 1934 1,997,366 Kern Apr. 9, 19352,063,541 Ellis Dec. 8, 1936 2,063,869 Ellis Dec. 8, 1936 2,081,889Borglin May 25, 1937 2,197,383 Outterson Apr. 16, 1949 2,230,230 BoggsFeb. 4, 1941 2,249,118 De Witt July 15, 1941 2,315,675 Trommsdorfif Apr.6, 1943 2,380,043 Hochwalt July 10, 1945 2,383,933 Bump Sept. 4, 19452,385,794 Chappell Oct. 2, 1945 2,386,033 Chappell Oct. 2, 19452,418,450 Auer Apr. 8, 1947 FOREIGN PATENTS Number Country Date 355,281Great Britain Aug. 12, 1931 OTHER REFERENCES Ind. and Eng. Chem, vol.22, pages 272-278, 1940.

Manufacture of Pulp and Paper, 2nd ed., vol. IV, Sec. 4, pages 40, 42and 48-51; pub. by McGraw-Hill, New York (1927) Wilson et al.: PaperTrade J., vol. 117, No. 21; 29-34 (1943).

Bainbridge: Institute of Paper Chem. Bull, vol. 15, p. 468 (1945).

6. PAPER SIZE WITH 1/4 TO 4% OF ROSIN, 1 TO 5% OF ALUMINUM SULFATE BASEDON THE FIBER, AND 20 TO 50%, BASED ON THE WEIGHTT OF THE ROSIN, OF THEREACTION PRODUCT OF ONE MOL OF ROSIN WITH FROM ABOUT ONE-QUATER TO ONEMOL OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF MALEIC, FUMARIC,ITACONIC AND CITRACONIC ACIDS AND THEIR ANHYDRIDES.